Radial piston pumps



u y 7, 1970 F. 5. FREEMAN 3,518,919

RADIAL PISTON PUMPS Original Filed Jan. 22, 1968 INVE NTOR ATTORNEYS United States Patent US. Cl. 91475 1 Claim ABSTRACT OF THE DISCLOSURE A pump comprising a body part containing a rotor with radially reciprocable pistons in bores thereof, a ring against an internal surface of which the pistons bear, an inlet and an outlet for liquid to be pumped and a part between an apertured side face of the rotor and the portion of the body part in which the outlet is formed, said part having a port through which liquid flows from the bores, to the outlet and said part being disposed so that the port occupies a plane which is inclined to the line of action of the biasing means.

This application is a continuation application of application 699,680 filed Jan. 22, 1968, now abandoned.

The invention relates to liquid pumps of the kind including a rotor supporting a plurality of radially reciprocable pistons, the pistons engaging a surface which, for the purpose of pumping liquid, is eccentric with respect to the axis of rotation of the rotor, said rotor being mounted within a body part in which are defined inlet and outlet ducts for the liquid.

The invention will now be described by way of example with reference to the accompanying drawings in which:

FIG. 1 is a side elevation cross-sectional view of a pump constructed in accordance with the invention, and

FIG. 2 is a view of one interior end face of the pump with the rotor and pistons omitted.

The pump illustrated has a body part incorporating a detachable end cover 11 at one end. Within the body part is defined a cavity 12 within which is rotatably mounted a rotor 13. The rotor 13 has a plurality of radially extending bores 14 containing respective pistons 15. Slippers 16 incorporated in the outer ends of the pistons bear against the internal surface of a ring 17 mounted in the body part 10. The internal surface of the ring 17 is part-spherical.

The rotor 13 has an integral tubular driving shaft 18 extending out of the body part 10 at its end remote from the end cover 11, and this shaft 18 is mounted in a hearing 19 in the body part 10.

Acting against the ring 17 is a coiled compression spring 20 arranged to urge the ring 17 towards a position (illustrated in FIG. 1) in which the ring and rotor are eccentric with respect to one another.

The side face of the rotor 13 adjacent to the end cover 11 is provided with a plurality of holes 21 communicating with the bores 14 respectively. The body part 10 has an inlet 22 and the end cover 11 has an outlet 23 for liquid to be pumped.

Between the end cover 11 and the adjacent end of the rotor 13 is a part 24 in which is formed a kidney shaped port 25 affording communication between the holes 21 in the rotor 13 and the outlet 23.

This part 24 is shown in FIG. 2 and remains stationary when the rotor is rotating. Inlet to the bores 14 through the holes 21 occurs as the rotor rotates when they are out of contact with the part 24.

As shown in FIG. 2 the part 24 is symmetrical about a plane which is identified 'by numeral 26, this plane passing ice through the axis of rotation of the rotor which is identified by numeral 27. This plane is inclined to the axis of the spring 20 (identified by numeral 28) which also passes through the axis 27.

In use, there exists a force which is the resultant of the forces applied by the pistons 15 to the ring 17, this resultant force tending to move the ring towards a position in which the ring 17 and rotor 13 having their axes substantially coincident. Movement under the action of this force takes place against the spring 20 and only occurs when the value of the force in the plane of the spring axis exceeds the spring rating.

The off-set position of the part 24 changes the direction of the resultant force mentioned from that which exists if the plane 26 is perpendicular to the axis 28 of the spring 20. The resultant force acts instead in a direction away from a point of contact between the exterior of the ring 17 and the interior cylindrical surface of the cavity 12 of the body part 10.

The ring 17 is constrained to move against the action of the spring towards a position in which axes of the ring and rotor are truely coincident. The sides of the cavity 12 may includes parallel straight portions parallel to the axis 28 these portions guiding the ring 17.

Alternatively a roller is incorporated into the wall of the cavity 12 to form a fulcrum about which the ring will move.

In a further alternative, the spring 20 is replaced by a diamond shaped blade spring, the line of action of this however, being identified by the plane 28 in the FIG. 2 construction.

I claim:

1. A radial piston type pum comprising a body part, an inlet and an outlet in the body part for liquid, a rotor mounted in the body part for rotation about an axis, a plurality of pistons occupying radially extending bores in the rotor respectively, a ring disposed within the body part, said ring providing an internal surface against which the outer ends of the pistons bear, biasing means acting between the body part and said ring having an axis passing through the axis of rotation of the rotor, the biasing means urging the ring towards a position in which said surface thereon is eccentric with respect to the axis of rotation of the rotor, axially extending holes in the side of the rotor, said holes communicating with the inner ends of the bores respectively, and a port plate disposed between said side of the rotor and the body part, the port plate having a port affording communication between the holes in the rotor in turn as the rotor rotates and the outlet in the body part, said port plate being disposed symmetrically about a plane passing through the axis or rotation of the rotor and being inclined with respect to the axis of the biasing means which also passes through the axis of rotation of the rotor.

References Cited UNITED STATES PATENTS 2,429,011 10/ 1947 Wylie.

2,518,578 8/1950 Tomlinson.

2,716,945 9/ 1955 Presnell.

2,797,643 7/1957 Sherman 103-161 X 2,871,797 2/ 1959 Bourassa.

3,064,583 11/1962 Burt.

3,096,723 7/ 1963 Puryear.

WILLIAM L. FREEH, Primary Examiner US. Cl. X.R. 91491 

